wcc: reject exported/bodyless/duplicate @test shapes

Both frontends, byte-stable fragments; -T-mode checks, so the rows
live in test/package (the fixture compile cell cannot reach -T).

test/package/package_test.ww

@@ -443,6 +443,52 @@ fn packagepath(relative: str) str = {
 	clean(root);
 };
 
+// Invalid @test attribute shapes reject at build with stable text on
+// BOTH frontends (the -T synth checker owns them; the fixture corpus
+// cannot reach -T, so these rows live here). Fragments only — the
+// stages' error-line prefixes legitimately differ (file:line:col vs
+// file:).
+@test fn invalid_test_shapes_reject() void = {
+	let root: str = fresh();
+	let shapes: []str = [
+		"@test export fn t() void = { };",
+		"@test fn t() void;",
+		"@test fn t(x: i32) void = { };",
+		"@test fn t() i32 = { return 0; };",
+		"@test @test fn t() void = { };",
+	];
+	let frags: []str = [
+		"@test fn 't' cannot be exported",
+		"@test fn 't' needs a body",
+		"@test fn 't' must be fn() void",
+		"@test fn 't' must be fn() void",
+		"duplicate @test on fn 't'",
+	];
+	let digits: []str = ["0", "1", "2", "3", "4"];
+	let outc: commandout;
+	let outw: commandout;
+	let i: i32 = 0;
+	for (i < shapes.len) {
+		let dir: str = strings.concat(root, "/shape", digits[i]);
+		assert(os.mkdir(dir, 448i32) == 0);
+		let src: str = strings.concat(dir, "/bad_test.ww");
+		writefile(src, strings.concat("package main;\n",
+			shapes[i], "\n"));
+		let avc: []str = [driver("ww"), "test", src];
+		let avw: []str = [driver("ww_ww"), "test", src];
+		runcommand(root, strings.concat("shape-c", digits[i]), avc,
+			(30i64 * (time.second: i64)): time.duration, &outc);
+		runcommand(root, strings.concat("shape-ww", digits[i]), avw,
+			(30i64 * (time.second: i64)): time.duration, &outw);
+		expectexit(&outc, 1);
+		expectexit(&outw, 1);
+		assert(has(outc.stderr, frags[i]));
+		assert(has(outw.stderr, frags[i]));
+		i += 1;
+	};
+	clean(root);
+};
+
 // Go's ./... parity: a trailing "..." element walks the tree, one package
 // run per test-bearing directory, dot- and underscore-prefixed directory
 // names excluded. The excluded sentinels hold failing tests so a wrong